Do *ANY* NiMH batteries actually work?

Question

My video shoots use a lot of AA & AAA batteries. I tried Li then NiMH rechargeables, to ensure I start shoots with fully charged batteries, and avoid mounds of half-spent batteries after a shoot (to figure out how to get the value out of).

But every single brand of rechargeable I've bought has been terrible. Even brand new, they hold WAY less mA-hr than alkaline. And the claimed low self-discharge rate of NiMH has turned out to be marketing-speak garbage. Most of mine lose 20-50% of their charge in a day or so. Some take a few months to get that bad. Others start off that bad right out of the retail packaging.

I've always bought big name brands with lots of reviews, and mostly >4/5 stars. But this has not helped at all.

My question: has anyone found tricks or brands for better results? Periodically fully discharging mine has not helped.

This AA & AAA rechargeable battery performance is in marked contrast to the device-specific OEM batteries (for cameras/camcorders/DARs/etc.) and most USB external batteries, which tend to perform well for at least 2-3 years. So, apparently the technology exists to make a battery that doesn't lose capacity and lose charge so quickly. But no one seems to be putting that better build tech into AAs & AAAs.

FWIW, my experience with AAAA rechargeables has been even worse, with about half leaking white powder from the cathode upon first charge (using an excellent/proven-good charger), and all getting returned. (I see Amazon has since stopped selling the ones I'd tried.)

Answer 1

I've had good luck with Eneloop batteries. One problem with NiMH batteries is that they produce a lower voltage than standard alkalines. NiMH batteries produce ~1.25 volts (vs 1.5 volts for alkys) for most of their life. (may start at ~1.35v freshly charged) Equipment that's not 'NiMH aware' might complain that the batteries are almost dead when they are actually OK, and that 1.35v drops to 1.25 pretty fast.

Alkaline AA cells can have a capacity of 1500 to 2000ma depending on the brand. Eneloop NiMH cells can have a capacity of 1800 to 2500ma. The useful life of these cells varies according to the application. An example that comes to mind is camera external flash. In my experience, the intermittent high current requirements of a flash will drain alkalines quickly, while NiMH cells do quite well.

Answer 2

If you want them to last months waiting for use, your only problem is in not buying the proper NiMH battery choice.

AA NiMH have MUCH more power capacity that alkalines. This may not be significantly noticeable for low drain devices like mp3 players, but it is all important for the high drain in cameras and flashes.

That is speaking of any NiMH, however regular NiMH "leak" to self discharge. Not in a few days, and not in corrosive leakage, but over a couple of months the regular NiMH lose considerable power capacity just sitting on the shelf. Then if it has been a month or two, you simply need to recharge them before next use. NiCd was real bad that way too.

However there have been gains in technology preventing that loss, in the newer NiMH batteries now called "low self discharge", or maybe "ready for use". "Ready for Use" units were not completely charged at the factory, but nevertheless, Ready to Use means they will survive months of sitting on the sales shelf, waiting to be purchased. The older NiMH technology does not say that. But be sure you properly charge any of them.

This is a Panasonic Eneloop diagram, a bit idealized, but supposedly for a 1/2 amp current continuous load. Camera flashes might hit 8 or 10 amps (for a couple of seconds of recycle), and alkaline are inadequate for that, but the NiMH can provide it.

By brand name, Eneloop NiMH (now from Panasonic) were the first with these low discharge batteries, but they license it to several other brands now. The big deal is that they claim 70% capacity remains after 5 years of storage on the shelf. That is NOT the ordinary NiMH batteries, but in these newer low self discharge choices like Eneloop.

Answer 3

I use eneloop pro for often used cameras. As opposed to the regular eneloops, they have a larger capacity per charge but quite less capacity per lifetime, a higher self-discharge rate but deliver higher current. That makes them recharge flashes quite faster. For a camera only used with external flashes or used rather irregularly (like a camera kept around for accident documentation at work or car), I'd likely rather use the regular eneloop.

Note that either stores typically less energy than Alkalines because of their lower voltage: the main advantage is the rechargeability. Also I use Panasonic's own dedicated smart chargers in order to avoid shortening battery life by cutting corners (time or charge current structure) bad for the batteries.

Sorry if this sounds like a brand ad: it seems like this is the main brand that does not yield to the temptation to eventually offer larger (sometimes nominal since they may not even survive shelf life) capacities at the cost of a construction seriously affecting battery lifetime and instead sticks with working design connected with branding so that they remain a dependably available choice.

With non-standard forms (laptop or phone batteries) they aren't available and my general experience is that the ridiculously expensive original parts tend to have considerably more lifetime than any third-party replacement batteries, even though the latter advertise larger capacities.